就航後長期間経過船の残留応力計測結果

抄録

What residual stresses would be retained in ships in prolonged sea service was the theme addressed by the authors, and a 20-year-old 33,375 D.W.T. tanker was selected for the measurement of residual stresses in welded joints in its upper deck, side shell, strut, bottom transverse members, and longitudinal members. The results may be capsulized as follows, (1) The butt joints in upper deck, side shell, etc. gave residual stress readings about as high as the base metal yield stress, indicating almost no changes in their residual stress levels from the 20 years of sea service. (2) Some of the boxing-fillet-welded joints joining the stiffeners or brackets to the face plates of longitudinal members exhibited the reduction in their intrinsically high levels of welding-induced tensile residual stress, probably from the effects of high tensile loads applied. It however was indeterminable whether such tensile loads had been applied in the course of ship construction or while at sea after being commissioned in service.